Stabilized liquid petroleum lubricant



2,967,829 STABILIZED LIQUID PETROLEUM LUBRICANT Edward 0. Bennett, Houston, Tex., assignor to Commercial Solvents Corporation, Terre Haute, Ind., a corporation of Maryland No Drawing. Filed June 27, 1958, Ser. No. 744,925

6 Claims. (Cl. 252-515) My invention relates to a stabilized petroleum lubricant and more particularly to a process for the production of stabilized petroleum lubricants containing as the active stabilizing agent nitroesters having the structural formula:

NO, B A-R R is selected from the group consisting of hydrogen, halo, methyl, ethyl and propyl; R is selected from the group consisting of methyl, ethyl, propyl and acyloxyalkyl with the proviso that at least one acyloxyalkyl radical is present; wherein the acyloxy and alkyl radicals contain 1-3 carbon atoms each.

It is well known that organisms from the groups consisting of Corynebacteriurn, Achromobacter, Pseudomona, Nocardia and Mycobacterium metabolize petroleum hydrocarbons and fatty acids and thereby produce undesirable oxidation products.

The petroleum industry has long been interested in the stabilization of various petroleum products such as cutting oils, hydraulic fluids, etc., against breakdown by bacteria which metabolize the hydrocarbons with the concurrent formation of deleterious metabolites.

Many compounds have been used as stabilization agents in lubricants, but very few have been found to be commercially successful due to the fact that the compounds are unstable, or are not active against a wide variety of microorganisms.

Among the compounds included within the scope of my invention are Z-nitro-l-propyl-l-butylformate, 2-nitro- 2-bromo-1-propylacetate, 2-nitro-2-ethyl-1,3-propanediol dipropionate, 2-nitro-2-chloro-1,3-propanediol diacetate, 2-nitro-2-methyl-l-propylacetate, etc. I have found that in some instances I can obtain total inhibition of bacterial growth in petroleum lubricants at concentrations as low as 100 parts per million. I prefer to include at least 1000 parts per million in most petroleum formulations. How- 'ever, I can employ amounts up to 2% by weight of the active nitroesters when the latter is soluble to this extent in the particular petroleum hydrocarbon composition.

I have found that my active ingredients are effective bacteriostatic agents in petroleum containing lubricants such as cutting oils, penetrating oils, grinding lubricants, iron tinning lubricants, core oils, hydraulic fluids, etc.

The following examples set out lubricating compositions in which my active ingredients act as effective bacteriostatic agents. It is not intended that my invention be limited to the compositions, portions, or lubricants set out below, but rather I intend for all equivalents and varia tions obvious to those skilled in the art to be included within the scope of this specification and the attached claims.

Example I My active ingredients were tested in a 25:1 water-cutting oil emulsion. The cutting oil concentrate used was a proprietary cutting oil containing no bacterial inhibitors States Patent hce sold by the Texas Company under the trade name Soluble Oil TL-3337. Six 3000 ml. portions of the water-cutting oil emulsion were placed in large mouthed one gallon glass containers. Desired amounts of my nitroesters were added to the cutting oil emulsion. No inhibitor was added to one 3000 ml. portion of the cutting oil emulsion which was used as a control. At the beginning of the experiment each unit was inoculated with 5 mls. of a heterogeneous bacterial culture which had grown for several years in a water-cutting oil emulsion. Aeration and mixing were obtained by bubbling compressed air through the emulsion. Water was added to each portion of the emulsion at periodic intervals in order to keep the volume of the units constant and to prevent concentration of the inhibitor by evaporation.

The following table sets out the results from the above tests and the number of days of total bacterial inhibition when the described concentration of the desired nitroester was incorporated into the cutting oil emulsion.

Example [I The following is a water emulsifiable cutting oil which is adequately protected by 1000 parts per million'of my nitroester inhibitors.

Light mineral oil Percent by weight" Oleic acid percent 10 Example 111 The following is a stabilized steam cylinder oil which is adequately protected by 100 parts per million-of 2-nitro- 2-bromo-1-propylacetate.

Percent S.A.E. lubricating oil Oleic acid 10 Example IV The following is a core oil which is adequately protected by 1000 parts per million of 2-nitro-2-methyl-l-propylacetate.

Percent Crude tall oil 25 Fuel oil 35 Tall oil ester (glycol or glycerol) 40 Example V The following is a cutting oil which is adequately protected by 1000 parts per million of 2-nitro-2ethyl-1,3- propanediol dipropionate.

Percent Tallow 65 Parafiin wax 29 Bees wax 1.3 Oxalic acid 1.3 Potassium citrate 1.3 Urea 0.4

Now having described my invention what I claim is:

1. A liquid petroleum lubricant composition consisting essentially of a liquid petroleum hydrocarbon and a suflicient amount of a nitroester to stabilize said hydrocarbon wherein R is selected from the group consisting of hydrogen, halo, methyl, ethyl, and propyl; R is selected from the group consisting of methyl, ethyl, propyl, and acyloxyalkyl with the proviso that at least one acyloxyalkyl radical is present; wherein the acyloxyl and alkyl radicals contain 1 to 3 carbon atoms each.

2. The composition of claim 1 wherein the compound is 2-nitro-2-bromo-1-propylacetatc.

3. The composition of claim 1 wherein the compound is 2-nitro-2-ethyl-1,3-propanediol dipropionate.

4. The composition of claim 1 wherein the compound is 2-nitro-2-chloro-1,3-propanediol diacetate.

5. The composition of claim 1 wherein the compound is 2-nitro-2-methyl-l-propylacetate.

6. A liquid petroleum lubricant composition consisting essentially of a liquid petroleum hydrocarbon and more than 100 ppm. of a nitroester to stabilize said hydro- 4 carbon against metabolizing bacteria, said nitroester having the following structural formula:

wherein R is selected from the group consisting of hydrogen, halo, methyl, ethyl, and propyl; R is selected from the group consisting of methyl, ethyl, propyl, and acyloxyalkyl with the proviso that at least one acyloxy radical is present; wherein the acyloxy and alkyl radicals contain 1 to 3 carbon atoms each.

References Cited in the file of this patent UNITED STATES PATENTS 1,502,174 Chapman July 22, 1924 2,427,821 Tindall Sept. 23, 1947 2,581,120 Matuszak Jan. 1, 1952 2,763,962 Hardy Sept. 25, 1956 OTHER REFERENCES Lubrication Eng, March 1957, pages 151-153. 

1. A LIQUID PETROLEUM LUBRICANT COMPOSITION CONSISTING ESSENTIALLY OF A LIQUID PETROLEUM HYDROCARBON AND A SUFFICIENT AMOUNT OF A NITROESTER TO STABILIZE AID HYDROCARBON AGAINST METABOLIZING BACTERIA, SAID NITROESTER HAVING THE FOLLOWING STRUCTURAL FORMULA: 